At 03:08 PM 7/04/2009, you wrote:
the chart attached is to help out those with a mind to electric
launch potential for self launch or sustainer sailplanes
Emilis,
Your PC date is a day behind.
Nice chart but that refers to the bare cells. Also Lithium Iron
Phosphate isn't anywhere near the energy density of Li -ion or LiPo
based on a couple of manufacturers I've seen. A123 and Thundersky.
Barely better than good NiMh at 4 times the price.
For Li-ion and LiPo you need a fair bit of physical protection and
protection and monitoring circuitry as well as balancing
chargers(basically charge each cell separately) Hence the Tesla car
gets about 107KW-hours per Kg according to an engineer I know who
looked into it whereas the cells themselves get around 150Kw-Hr/Kg.
The Antares cells are Saft VL41M of about 136 Kw-hr/kg but when all
the mounting/heating/protection and monitoring stuff is added up you
get around 100KW-hr/kg which for now seems to be a good number to work on.
The Antares battery pack is quoted at Euro 15,000 for replacement.
Tesla will give you a new pack in 3 years for US$12,000 now upfront
as they claim the pack is actually worth US$36000 to replace. You
better hope the company is around in 3 years of course.
I could just get 6.5Kw-hr in the Ventus fuselage without exceeding
the max NLP weight along with 15Kg of engine prop/extension system
which would make a sort of OK motorglider if you didn't use water
ballast. About 2.5 Kw-hr for a launch and 4 Kw-hr for retrieve. So
what's 2.5Kw-hr of electricity worth from the mains? Under 40 cents anyway.
Mike
Borgelt Instruments - manufacturers of quality soaring instruments
phone Int'l + 61 746 355784
fax Int'l + 61 746 358796
cellphone Int'l + 61 428 355784
Int'l + 61 429 355784
email: [email protected]
website: www.borgeltinstruments.com
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